The subject invention relates generally to turbomachinery. More particularly, the subject invention relates to flow inhibitors for turbomachinery.
A turbomachine, for example, a gas turbine typically includes at least one inner shroud supported in the turbomachine by at least various components including an outer shroud. The inner shroud is located directly downstream of a row of turbine nozzles and is exposed to gas temperatures high enough to require that the inner shroud be actively cooled or damage to the inner shroud would result from the exposure. The outer shroud, however, is typically not actively cooled since it is not directly in the gas path.
Hot gas is often ingested by the turbomachine into an axial gap which is typically between the turbine nozzles and the inner shroud. Hot gas flow entering this gap may, if not stopped or otherwise mitigated, advance to reach the outer shroud and cause damage to the outer shroud. The ingestion is often caused in part by a circumferential pressure gradient primarily resulting from the close proximity of a trailing edge of the nozzles and a forward edge of the inner shroud. The circumferential pressure gradient forces hot gas into the gap.
One measure used to prevent damage to the outer shroud is to inject secondary cooling air from the inner shroud into the gap between the turbine nozzles and the inner shroud to prevent hot gas from reaching the outer shroud. This method, however, decreases performance of the turbomachine, and the art would well receive a structure or method to prevent damage to the outer shroud from hot gas ingestion that does not negatively impact engine performance.